Most types of nuclear power reactors use fuel in the form of high density-uranium dioxide pellets clad in Zircaloy. Sinterable uranium dioxide powder is usually produced via the ammonium diuranate (ADU) route. This involves dissolution of uranium ore concentrates (yellow cake) in nitric acid, purification by solvent extraction using tributyl phosphate in kerosene, precipitation of ADU, filtration, drying, calcination and reduction with hydrogen to give uranium dioxide powder. The AAEC has carried out pilot plant development of these processes to demonstrate the production of nuclear grade uranium dioxide from Australian yellow cake and to improve the processes and technology wherever possible.